This project proposes to study beta-thalassemia trait in health maintenance organization in order to evaluate 1) the educational efficacy and psychological impact of screening and genetic counseling, and 2) methods suitable for large-scale screening for this condition. Regarding the genetic counseling, the specific aims are: 1) To evaluate effects of characteristics of the counselee and of the counseling method on: a) Comprehension (information retained, misinformation acquired, ability to reason with concepts and attitudes acquired), b) Psychologic impact (affective response, coping, self-image), c) Changes in behavior (reproductive, marital, sexual, health-related). 2) To determine which features of the counselee or counseling strategy predispose to optimal results in la, lb, or lc. 3) To provide an empirical basis for cost-benefit analysis with regard to counseling method in mass screening.